Author

Date of Award

Degree Type

Degree Name

Department

First Advisor

Gary Ritchison

Department Affiliation

Biological Sciences

Second Advisor

David R. Brown

Department Affiliation

Biological Sciences

Third Advisor

Luke E. Dodd

Department Affiliation

Biological Sciences

Abstract

Many species in the family Corvidae, including Blue Jays (Cyanocitta cristata), are known to have large vocal repertoires. However, perhaps due to its perceived complexity, few investigators have attempted to describe the vocal repertoire of Blue Jays. Therefore, my objectives were to describe the vocal repertoire of Blue Jays, determine the characteristics of their calls, and suggest possible functions. During 2015 and 2016, I studied free-living Blue Jays in and near Richmond, Madison County, Kentucky. I observed Blue Jays at 17 different locations, recorded their vocalizations, and noted the behavioral contexts during which calls were uttered. I also conducted playback experiments with four different Blue Jay calls and with the calls of several species of raptors to provide additional contexts that might provide insight into call function. I recorded 7213 calls uttered during 488 vocal bouts during 103 observation sessions, and identified 40 distinct call types distinguished by their characteristics (peak frequency, high frequency, low frequency, frequency range, and duration). Three call types were only uttered by nestling and fledgling Blue Jays, and two call types were only uttered by adult Blue Jays during playback experiments. Some call types were used more often during either the breeding or non-breeding season and in certain behavioral contexts, suggesting that they served particular functions. However, most call types of adult Blue Jays were used throughout the year and in a variety of behavioral contexts, making it difficult to determine possible functions. Differences in call types used and use of the same calls in different contexts by Blue Jays at different locations suggest that they learn some call types in their vocal repertoires. Further, Blue Jays at different locations or in different flocks may have distinct vocal repertoires and particular calls may serve different functions. A possible explanation for the large vocal repertoire of Blue Jays and other species of birds is the social complexity hypothesis. Species, like Blue Jays, that regularly interact with large numbers of conspecifics in a variety of behavioral contexts are more likely to benefit from having larger vocal repertoires than solitary or less social species. Additional detailed study of species of songbirds with large vocal repertoires, including Blue Jays, will improve our understanding of how such repertoires are used as well as the selective pressures that have favored their evolution.